Add a tool to look for source files that have unneeded grit header includes.

tools/unused-grit-header.py

Index: tools/unused-grit-header.py
diff --git a/tools/unused-grit-header.py b/tools/unused-grit-header.py
new file mode 100755
index 0000000000000000000000000000000000000000..37c734e84bbed63dce09068f29a9115b04e28bb0
--- /dev/null
+++ b/tools/unused-grit-header.py
@@ -0,0 +1,201 @@
+#!/usr/bin/env python
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""A tool to scan source files for unneeded grit includes."""
+
+import os
+import sys
+import xml.etree.ElementTree
+
+IF_ELSE_TAGS = ('if', 'else')
+
+
+def Usage(prog_name):
+  print prog_name, 'GRD_FILE DIRS_TO_SCAN'
+
+
+def GetResourcesForNode(node, parent_file, resource_tag):
+  """Recursively iterate through a node and extract resource names.
+
+  Args:
+    node: The node to iterate through.
+    parent_file: The file that contains node.
+    resource_tag: The resource tag to extract names from.
+
+  Returns:
+    A list of resource names.
+  """
+  resources = []
+  for child in node.getchildren():
+    if child.tag == resource_tag:
+      resources.append(child.attrib['name'])
+    elif child.tag in IF_ELSE_TAGS:
+      resources.extend(GetResourcesForNode(child, parent_file, resource_tag))
+    elif child.tag == 'part':
+      parent_dir = os.path.dirname(parent_file)
+      part_file = os.path.join(parent_dir, child.attrib['file'])
+      part_tree = xml.etree.ElementTree.parse(part_file)
+      part_root = part_tree.getroot()
+      assert part_root.tag == 'grit-part'
+      resources.extend(GetResourcesForNode(part_root, part_file, resource_tag))
+    else:
+      raise Exception('unknown tag:', child.tag)
+  return resources
+
+
+def FindNodeWithTag(node, tag):
+  """Look through a node's children for a child node with a given tag.
+
+  Args:
+    root: The node to examine.
+    tag: The tag on a child node to look for.
+
+  Returns:
+    A child node with the given tag, or None.
+  """
+  result = None
+  for n in node.getchildren():
+    if n.tag == tag:
+      assert not result
+      result = n
+  return result
+
+
+def GetResourcesForGrdFile(tree, grd_file):
+  """Find all the message and include resources from a given grit file.
+
+  Args:
+    tree: The XML tree.
+    grd_file: The file that contains the XML tree.
+
+  Returns:
+    A list of resource names.
+  """
+  root = tree.getroot()
+  assert root.tag == 'grit'
+  release_node = FindNodeWithTag(root, 'release')
+  assert release_node != None
+
+  messages_node = FindNodeWithTag(root, 'messages')
+  messages = set()
+  if messages_node != None:
+    messages = set(GetResourcesForNode(messages_node, grd_file, 'message'))
+
+  includes_node = FindNodeWithTag(root, 'includes')
+  includes = set()
+  if includes_node != None:
+    includes = set(GetResourcesForNode(includes_node, grd_file, 'include'))
+  return messages.union(includes)
+
+
+def GetOutputFileForNode(node):
+  """Find the output file starting from a given node.
+
+  Args:
+    node: The root node to scan from.
+
+  Returns:
+    A grit header file name.
+  """
+  output_file = None
+  for child in node.getchildren():
+    if child.tag == 'output':
+      if child.attrib['type'] == 'rc_header':
+        assert output_file is None
+        output_file = child.attrib['filename']
+    elif child.tag in IF_ELSE_TAGS:
+      child_output_file = GetOutputFileForNode(child)
+      if not child_output_file:
+        continue
+      assert output_file is None
+      output_file = child_output_file
+    else:
+      raise Exception('unknown tag:', child.tag)
+  return output_file
+
+
+def GetOutputHeaderFile(tree):
+  """Find the output file for a given tree.
+
+  Args:
+    tree: The tree to scan.
+
+  Returns:
+    A grit header file name.
+  """
+  root = tree.getroot()
+  assert root.tag == 'grit'
+  output_node = FindNodeWithTag(root, 'outputs')
+  assert output_node != None
+  return GetOutputFileForNode(output_node)
+
+
+def ShouldScanFile(filename):
+  """Return if the filename has one of the extensions below."""
+  extensions = ['.cc', '.cpp', '.h', '.mm']
+  file_extension = os.path.splitext(filename)[1]
+  return file_extension in extensions
+
+
+def NeedsGritInclude(grit_header, resources, filename):
+  """Return whether a file needs a given grit header or not.
+
+  Args:
+    grit_header: The grit header file name.
+    resources: The list of resource names in grit_header.
+    filename: The file to scan.
+
+  Returns:
+    True if the file should include the grit header.
+  """
+  with open(filename, 'rb') as f:
+    grit_header_line = grit_header + '"\n'
+    has_grit_header = False
+    while True:
+      line = f.readline()
+      if not line:
+        break
+      if line.endswith(grit_header_line):
+        has_grit_header = True
+        break
+
+    if not has_grit_header:
+      return True
+    rest_of_the_file = f.read()
+    return any(resource in rest_of_the_file for resource in resources)
+
+
+def main(argv):
+  if len(argv) < 3:
+    Usage(argv[0])
+    return 1
+  grd_file = argv[1]
+  dirs_to_scan = argv[2:]
+  for f in dirs_to_scan:
+    if not os.path.exists(f):
+      print 'Error: %s does not exist' % f
+      return 1
+
+  tree = xml.etree.ElementTree.parse(grd_file)
+  grit_header = GetOutputHeaderFile(tree)
+  resources = GetResourcesForGrdFile(tree, grd_file)
+
+  files_with_unneeded_grit_includes = []
+  for dir_to_scan in dirs_to_scan:
+    for root, dirs, files in os.walk(dir_to_scan):
+      if '.git' in dirs:
+        dirs.remove('.git')
+      full_paths = [os.path.join(root, f) for f in files if ShouldScanFile(f)]
+      files_with_unneeded_grit_includes.extend(
+          [f for f in full_paths
+           if not NeedsGritInclude(grit_header, resources, f)])
+  if files_with_unneeded_grit_includes:
+    print '\n'.join(files_with_unneeded_grit_includes)
+    return 2
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))